Insert the SD card in the host computer. A pop-up message should appear. Select the option Do Nothing, as illustrated in the picture below:

Select *do nothing* after SD card insertion

Notice that some SD cards have a physical lock that enables read-only mode, therefore you have to make sure this lock is not enabled. If the lock is enabled, further steps from this how-to section will not work.

List the hard-disks and partitions being used by your system. See the example below:

user@host:~$ df -h

Filesystem Size Used Avail Use% Mounted on

udev 3,9G 0 3,9G 0% /dev

tmpfs 792M 50M 743M 7% /run

/dev/sda7 42G 30G 10G 75% /

tmpfs 3,9G 145M 3,8G 4% /dev/shm

tmpfs 5,0M 8,0K 5,0M 1% /run/lock

tmpfs 3,9G 0 3,9G 0% /sys/fs/cgroup

/dev/sda5 922M 340M 520M 40% /boot

/dev/sda8 178G 28G 141G 17% /usr/local

/dev/sdb5 620G 558G 31G 95% /home

tmpfs 792M 92K 792M 1% /run/user/1000

/dev/mmcblk0p1 7,5G 296M 7,2G 4% /media/<user>/3E18-AADE

Notice that there is a new device, /dev/mmcblk0, and this is the SD card.

If you use an SD card to USB adapter, your device may be listed as /dev/sdX, being X a character that depends on how many disks your system have. For the computer from the exemple, the device is /dev/sdc:

/dev/sdc1 7,5G 296M 7,2G 4% /media/<user>/3E18-AADE

Attention: Proceed carefully through the next steps. If you use the wrong device, you will erase the computer hard-disk and permanently lose data.

Also create a label for your partition, such as data. This is not mandatory, but when the system automatically mounts the SD card, it will use this label as the name of the directory where the device will be mounted.

Mount the SD card. Two easy ways of doing it are:
- Either to click the SD card icon in the launcher to the left of the screen, or
- Open the files manager and click the SD card partition label listed at the left side of the window.

Both options are illustrated in the figure below:

Mount the SD card

Notice that the default mount path for Ubuntu is:

/media/<user>/<partition_label>

Where user is the user you are logged in, and partition_label is the label chosen at step 10, or a random alphanumeric value if the label was left blank.

Make sure that you have a working serial terminal application on your host machine.
Note: You can go back to the last section if there are any doubts regarding the serial terminal application and its configuration.

Plug the USB A to micro B cable into the USB Client Connector (x10) to enter the recovery mode.

USB A to micro B cable

USB A to micro B cable highlighted

Simultaneously apply power to the embedded system and press the SPACE key in your keyboard a few times, while focused in the serial terminal. If you are successful, this procedure will stop the bootloader and you will have a terminal with the following prompt: